Computer systems use Random Access Memories (RAMs) such as Dynamic RAM (DRAM) and Static RAM (SRAM) to store information. Generally, the DRAM has high speed read/write cycle time characteristics; however, it requires repeated replenishing of charge stored on the capacitors in order to retain the information. The SRAM stores information in flip-flop elements typically made up of four to six transistors. Both DRAM and SRAM are volatile memory devices.
A Magnetoresistive RAM (MRAM) device has been developed as a new type of memory, which is non-volatile. The MRAM has a plurality of memory cells. Each memory cell is a multilayered structure in which two layers of magnetic material are separated by a layer of non-magnetic metallic conducting material. Digital information is represented by the direction of magnetic vectors in the magnetic material. The information remains in a given state until it is intentionally changed by applying an opposite magnetic field that exceeds a threshold level.
In the prior art MRAM devices, a comparator is used for retrieving the digital information stored in the memory cells of the MRAM devices. To read the digital information stored in the memory cells, the comparator is initially "autozeroed." A problem with having an "autozero" step for retrieving digital information is that it increases the amount of time for the reading of the digital information, which decreases the overall speed of the MRAM device.
Accordingly, it would be advantageous to have an MRAM device and method for high speed operation of the device. It would be of further advantage for the MRAM device to have a high density, i.e., occupy a small area.